Reinforcement of the spine between the two vertebral bodies affected by the lesion is performed in a number of spinal lesions, especially lesions to intervertebral disks, such as spondylolisthesis and instability following disk herniation and stenosis. An interbody cage is inserted for this between the vertebral bodies into the scooped-out intervertebral disk space, and the vertebral bodies fuse with the cage. This is called, e.g., lumbar interbody fusion or LIF. There are similar methods for the thoracic spine and the cervical spine. A skin incision is usually made for this in order to be able to reach the intervertebral disk space under visible conditions, and this is accompanied by muscle destruction. In addition, percutaneous screws embedded by minimally invasive spinal surgery with screw-rod systems may contribute to the overall stabilization.
The prior-art techniques for gaining access for inserting cages into the intervertebral disk space between vertebral bodies are subject to drawbacks and risks.